We can thank Meg Ryan and Billy Crystal for spreading the good word about Katz’s far and wide, but longtime New Yorkers know this Jewish deli on Manhattan’s Lower East Side has been a neighborhood institution for roughly 130 years. Despite the attention that’s been lavished on this family-owned business, with countless book and travelogue show appearances glorifying the mystifyingly unctuous, smoky pink meat, Katz’s stays true to its roots. Fatty, navel-cut brisket, which can withstand long stints in a smoker, is cured with sodium nitrite-enriched salt for up to four weeks. Then, it’s rubbed down with a top-secret spice blend, and from there, it’s off to the smoker for two to three whole days. In the final phase, the meat is boiled and steamed, locking in the fatty juices that beg to be mopped up. (That’s where the rye comes in.) Dress it up with a swipe of Katz’s housemade spicy brown mustard — but don’t dare ask for ketchup. Or mayo. Or yellow mustard, for that matter. There’s only one way to eat Katz’s hot pastrami sandwich, and this is it.